学步园

 private void button1_Click(object sender, EventArgs e)
        {
            Regex reg = new Regex(@"^/d{0,3}$");
            if (reg.IsMatch(this.textBox1.Text) && reg.IsMatch(this.textBox2.Text))
            {
                int num1=int.Parse(this.textBox1.Text);
                int num2=int.Parse(this.textBox2.Text);
                int result=num1+num2;
                this.label3.Text = result.ToString();
            }
            else
            {
                MessageBox.Show("输入不合法");
            }
        }